SURFACE-ACTIVITY AND MICELLE FORMATION OF ANIONIC AZOBENZENE-LINKED SURFACTANTS

The adsorption phenomena and micellization of sodium 4-((4'-alkylpheny l)azo)benzenesulfonates C(n)AzoSO(3)Na (C-n = C2H5, C4H9, C8H17), and sodium 4-((4'-alkylphenyl)azo)benzoates, C(n)AzoCOONa (C-n = C4H9, C8H 17), were studied by means of surface tension and cyclic voltammetric (CV) techniques and compared with the respective parameters of the sta ndard sodium alkanesulfonates, sodium alkylbenzenesulfonates, and sodi um alkanecarboxylates. The presence of the azobenzene moiety in the su rfactant molecule as a link between the hydrophobic tail and the anion ic head group improves the surfactant solubility in water and introduc es the hydrophobic character comparable to the effect of 8.4 methylene groups of the main alkyl chain in the assumed standards, The hydropho bic nature of both phenylene groups attached to the azo entity depends upon the position of these groups in the hydrophilic/hydrophobic zone s.